Stereoscopic display device

ABSTRACT

To provide a naked-eye type stereoscopic display device which can achieve a fine stereoscopic display property while achieving high-definition display and high yield. Aperture parts of sub-pixels neighboring to a first direction include overlapping regions which overlap in a second direction and a non-overlapping region which does not overlap. Provided that a width of the aperture part in the second direction is defined as a longitudinal aperture width, the non-overlapping region includes an aperture width fluctuating region where the longitudinal aperture width changes continuously from roughly a center of the aperture part towards both ends of the first direction, respectively. The sum of the longitudinal aperture widths of the two overlapping regions overlapping with each other at a same position in the first direction is larger than the longitudinal aperture width in roughly the center of the aperture part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2014-258568, filed on Dec. 22, 2014, andJapanese patent application No. 2015-202118, filed on Oct. 13, 2015, thedisclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stereoscopic display device whichprovides stereoscopic images to observers with naked eyes.

2. Description of the Related Art

A naked-eye type stereoscopic display device does not require anyspecial eyeglasses, so that the observer can enjoy stereoscopic imagesreadily. With personal mobile terminals such as mobile phones,smartphones, and feature phones and household display devices such astelevision set receivers, such techniques for achieving in naked-eyetype stereoscopic display are being developed rapidly.

The naked-eye type stereoscopic display techniques achieve stereoscopicdisplay by giving directivity to the light emitted from a display andproviding parallax images to each of the both eyes of an observer.Examples thereof may be a 2-viewpoint stereoscopic image displaytechnique, a multiple-viewpoint stereoscopic image display technique,and an integral photography (IP) technique.

There are various members as a light-ray control module for giving thedirectivity to the emitted light. Examples thereof may be a type whichutilizes a lens or a barrier on the display surface and a type in whichthe light emitted from the display device itself has the directivity.

A display panel is typically formed by arranging, in a matrix form,pixels each displaying a minimum element of an image. In a naked-eyetype stereoscopic display device, it is necessary to display viewpointimages corresponding to the number of viewpoints. Thus, sub-pixels fordisplaying minimum elements of the viewpoint images are requiredfurther.

Note here that there are cases where an element having a colorexpressing function for displaying a color of an image is referred to asa “sub-pixel”. For example, such term is used in an expression “a pixelconstituted with sub-pixels of red, green and blue”. However, if it isnot specifically mentioned, the “sub-pixel” in the current Specificationis defined to be an element including a viewpoint image displayingfunction for convenience. Note that the sub-pixel in the currentSpecification can also include a color expressing function.

The sub-pixel is a device for converting an electric signal into anoptical signal. The region between a sub-pixel and another sub-pixel isa region where optical conversion cannot be done. When a part, which isnot intended to be viewed, in that region is viewed by an observer in anexpanded manner due to the light-ray control module, a sense ofdiscomfort is given to the observer. The state of such image quality isreferred to as 3D moiré.

As a countermeasure for 3D moiré, there is proposed a related techniquewith which an overlapping region is provided in optical aperture partsof two sub-pixels neighboring to each other in the viewpoint directionand the total values of the longitudinal aperture widths are set to beconstant (Japanese Unexamined Patent Publication Hei 10-186294 (PatentDocument 1)). Further, also proposed is a related technique with whichthe total values of the longitudinal aperture widths are set to beconstant by utilizing the sub-pixels arranged over a plurality of rows(Japanese Unexamined Patent Publication 2008-249887 (Patent Document2)). Furthermore, also proposed is a related technique with which thevisibility of 3D moiré is decreased by devising the longitudinalaperture widths in the overlapping regions of the sub-pixels (JapaneseUnexamined Patent Publication 2012-063556 (Patent Document 3)).

However, there is such an issue that the visibility of 3D moiré cannotbe decreased sufficiently even when the above-described relatedtechniques are used. This issue will be described in details hereinafterby using FIG. 15A to FIG. 17.

Referring to FIG. 15A, an ideal sub-pixel structure will be described.Two sub-pixels 400 and 500 are disposed neighboring to each other in afirst direction x. Lenses 1 as a light-ray control modules are disposedat positions corresponding to the sub-pixels 400, 500 along the firstdirection x repeatedly. Due to such structure, the first direction xcoincides with the light-ray separating direction. Note that shapes ofoptical aperture parts 410, 510 or the two sub-pixels 400, 500 areconsidered to be roughly in a parallelogram form for convenience sake interms of explanation.

First, considered is a case where the aperture part 410 is divided intotwo sections in the first direction x. In a certain section along thefirst direction x, the aperture part 410 overlaps with the aperture part510 in a second direction y. Such section is referred to as anoverlapping section 401L. Further, in the other section along the firstdirection x, the aperture part 410 does not overlap with the aperturepart 510 in the second direction y. Such section is referred to as anaperture width constant section 403.

Accordingly, the shape of the aperture part 410 is also considered bydividing it into two regions along the first direction x. Out of theaperture part 410, a region belonging to the overlapping section 401L isreferred to as an overlapping region 421L, while a region belonging tothe aperture width constant section 403 is referred to as an aperturewidth constant region 423. This can be considered the same in the caseof the neighboring aperture part 510. Out of the aperture part 510, aregion belonging to an overlapping section 501R is referred to as anoverlapping region 521R, while a region belonging to an aperture widthconstant section 503 is referred to as an aperture width constant region523. Note that the overlapping sections are the sections regulated byoverlap of the aperture parts 410 and 510 in the second direction y, sothat the positions of the overlapping sections 401L and 501R in thefirst direction x coincide with each other.

Now, the width of the second direction y out of the widths of theaperture part is defined as “longitudinal aperture width”. Thelongitudinal aperture widths 413, 513 of the aperture width constantregions 423, 523 are constant regardless of the positions in the firstdirection x. In the meantime, the longitudinal aperture widths 411L,511R in the overlapping sections 401L, 501R vary according to thepositions in the first direction x.

Further, at the same position in the first direction x within theoverlapping sections 401L and 501R, the value of “411L+511R” that is thesum of the longitudinal aperture widths 411L and 511R (referred to as“sum of longitudinal aperture widths” hereinafter) is constant. Further,the sum of the longitudinal aperture widths “411L+511R” and thelongitudinal aperture width 413 as well as the longitudinal aperturewidth 513 take the same values with each other.

Next, let's look into the total value of the longitudinal aperturewidths of a sub-pixel group arranged in the first direction among thesub-pixels arranged in matrix on a display panel. FIG. 15B is a graphshowing, with a plot 002, the relation between the positions in thefirst direction and the total value of the longitudinal aperture widthsin the ideal sub-pixel structure shown in FIG. 15A. Note here that thetotal value of the longitudinal aperture widths is the sum of the twolongitudinal aperture widths “411L+511W” in the overlapping sections401L and 501R. It is the value of the longitudinal aperture width 413 inthe aperture width constant section 403, while it is the value of thelongitudinal aperture width 513 in the aperture width constant section503.

As described above, the sum of the longitudinal aperture widths“411L+511W”, the longitudinal aperture width 413, and the longitudinalaperture width 513 take the same values with each other, so that theplot 002 is always constant for the positions in the first direction x.Thereby, generation of 3D moiré in the light-ray separating direction isto be suppressed.

Incidentally, there are various elements for constituting the opticalaperture shapes of actual sub-pixels depending on the types of theelectro-optical elements. Examples thereof are a black matrix, signalwirings, and the like in a liquid crystal display, partition walls,display electrodes and the like in a plasma display, a light emissionlayer region, signal wirings, and the like in an organic EL display.Each of those elements is manufactured by using a photolithographytechnique in general. Thus, the precision of those shapes depends on thepattern precision of the photolithography technique.

Considering the currently used typical materials and manufacturingdevices for photolithography, it is difficult to completely eliminateprocessing variation of about several μm as the shape precision.Further, in order to control the processing variation to be less thanthe order of sub-μm level, expensive materials and manufacturing devicesare required. Thus, it is difficult to provide inexpensive stereoscopicdisplay devices. There is not a little shape dependency existing in theprocessing variation. Especially, the processing precision variation ofa bent shape including an acute angle is relatively large. Due to theprocessing precision variation, fluctuation may be generated in thequality of the acquired products, e.g., the corner of the opticalaperture part of the sub-pixel may be rounded, the optical aperture partmay become small or large as a whole, and the like.

FIG. 16A is an explanatory chart showing changes in the longitudinalaperture width when the corner of the aperture part is rounded withrespect to the ideal sub-pixel structure shown in FIG. 15A. The idealsub-pixel aperture parts 410, 510 and the aperture parts 410 a, 510 a ofthe sub-pixels 400 a, 500 a having rounded corners P, Q are illustratedin a corresponding manner.

The overlapping sections 401 aL, 501 aR of the aperture parts 410 a, 510a having the rounded corners P, Q become smaller than the overlappingsections of the ideal aperture parts 410, 510. Further, because of thischange, an aperture width fluctuating section 402 aL appears between theoverlapping section 401 aL and the aperture width constant section 403a, and an aperture width fluctuating section 502 aR appears between theoverlapping section 501 aR and the aperture width constant section 503a. Those aperture width fluctuating sections 402 aL, 502 aR aregenerated when the parts to become overlapping sections with the idealaperture parts 410, 510 come to have the rounded corners P, Q due to theprocessing precision variation so that the aperture parts do not existin those sections.

FIG. 16B shows the results acquired by paying attention to the positionsin the first direction and the total values of the longitudinal aperturewidths of the sub-pixel group arranged in the first direction in suchcase. That is, FIG. 16B is a graph showing the relation between thepositions in the first direction and the total values of thelongitudinal aperture widths regarding the aperture part having therounded corner.

As shown with a plot 002 a in FIG. 16B, in accordance with theappearance of the aperture width fluctuating sections 402 aL, 502 aRcaused by the influence of the rounded corners Q, P, positions S, T atwhich the value of the longitudinal aperture width radically decreasesin those sections are generated locally. The value of the sum of thelongitudinal aperture widths “411 aL+511 aR” of the other overlappingsections 401 aL, 501 aR and each of the values of the longitudinalaperture widths 413 a, 513 a of the aperture width constant sections 403a, 503 a do not change since those are not affected by the roundedcorners P, Q.

There are a longitudinal aperture width change value Wq and alongitudinal aperture width change section Vq at the positions S and T.The longitudinal aperture width change value Wq depends on the angle θof a side (e.g., an aperture side 400 aA, 500 aB, or the like) existingin the overlapping section within the aperture part with respect to thefirst direction x. Further, the longitudinal aperture width changesection Vq depends on the size of the rounded corners P, Q in additionto the extent of the angle θ.

FIG. 17 is a graph showing the relations regarding the angle θ of theaperture part, the longitudinal aperture width change value Wq, and thelongitudinal aperture width change section Vq in a case where the cornerof the aperture part is rounded.

As shown in FIG. 17, when the angle θ becomes larger, the longitudinalaperture width change value Wq becomes larger while the longitudinalaperture width change section Vq becomes smaller. Inversely, when theangle θ becomes smaller, the longitudinal aperture width change value Wqbecomes smaller while the longitudinal aperture width change section Vqbecomes larger. Therefore, in terms of 3D moiré, it is advantageous tohave a smaller angle θ. However, when the angle θ is too small, theoverlapping section of the sub-pixels becomes extremely large so thatthe 3D crosstalk property tends to be deteriorated.

Further, in a case where the sub-pixel size and the layout pitch aredesigned to be small in accordance with the recent tendency ofultra-high definition, the angle θ also becomes large. Thus, 3D moiré isdeteriorated as described above. Therefore, with the ideal sub-pixelstructure shown in FIG. 15A, it is essential to deal with such issue.

FIG. 18 is a chart showing 3D moiré generated when the value of thelongitudinal aperture width is decreased radically due to rounding ofthe corner shown in FIG. 16B by using the relation between the observerand stereopsis regions. The lateral axis of FIG. 18 shows the observingangles in the first direction, and the longitudinal axis shows theluminance distribution with respect to the observing angles. The twokinds of dotted lines show the luminance distributions when an image isoutputted only to either one of the pixels, assuming that a sub-pixel400 a is a right-eye pixel and a sub-pixel 500 a is a left-eye pixel.That is, Y1 is the luminance distribution when white is displayed on theright-eye pixel and black is displayed on the left-eye pixel, Y2 is theluminance distribution when black is displayed on the right-eye pixeland white is displayed on the left-eye pixel, and Y3 is the luminancedistribution when white is displayed on the both pixels. Basically, therelation regarding the luminance can be expressed as Y3=Y1+Y2.

Note here that a right-eye observing region is 800R, and a left-eyeobserving region is 800L. As shown in FIG. 18, in a case where the botheyes of the observer are located at the centers of each of the observingregions, the observer does not recognize 3D moiré. However, in a casewhere the both eyes of the observer are located in the vicinity of theborders (e.g., positions T, S) of each of the observing regions, theobserver recognizes the radical luminance change and thereby perceives3D moiré.

Note that the 3D moiré is called herein as black moiré when the imageluminance is radically decreased. Inversely, it is called herein aswhite moiré when the image luminance is increased. FIG. 18 is a casewhere black moiré is generated.

When the ideal pixel shape shown in the related techniques is applied tothe actual display panel, 3D moiré is to be visually recognized due to asteep luminance difference generated according to shift in the observingposition caused by variation in the processing precision. As acountermeasure for that, it is considered to achieve an ideal shape byadding a correction pattern to the acute angle part, for example.However, in that case, even when the correction pattern is added, theprocessing precision variation cannot be absorbed sufficiently. Not onlythat, there still remains such an issue that the correction patternitself cannot be disposed or that the correction pattern cannot functionwhen high definition is advanced.

As a countermeasure for 3D moiré, considered is a method with which theluminance increase/decrease is eased by employing defocus of a lens.When employing defocusing, the distance from the lens vertex to thesub-pixel (referred to as “lens-pixel distance” hereinafter) is changedwith respect to the focal distance of the lens to “blur” the steepluminance difference for improving the 3D moiré. However, this means toshift the focal distance intentionally, so that the stereoscopic displayproperty typically 3D crosstalk is worsened.

Further, when using defocusing, it is important to keep the lens-pixeldistance constant with high precision. When variation in the lens-pixeldistance is large, defocusing is worsened further so that the 3Dcrosstalk property is deteriorated greatly. The 3D crosstalk hereinmeans a phenomenon where a certain viewpoint image is mixed into anotherviewpoint image and displayed when performing stereoscopic display. Inorder to keep the lens-pixel distance constant with high precision, highprocessing precision is required not only for the lens manufacturingtechnique but also for the display panel manufacturing technique.

In a display panel where sub-pixels of narrow pitch are disposed inmatrix for achieving higher definition, variation in the processingprecision becomes relatively larger. Thereby, the change in thelongitudinal aperture width becomes still greater. Further, the numberof the sub-pixels in the display region of the display panel having alarge number of pixels becomes relatively greater, so that it isnecessary to keep the processing precision over a wide range of thedisplay panel.

It is therefore an exemplary object of the present invention to providea naked-eye type stereoscopic display device which can achieve a finestereoscopic display property while achieving high-definition displayand high yield.

SUMMARY OF THE INVENTION

The stereoscopic display device according to an exemplary aspect of theinvention is a stereoscopic display device which includes: a displaypanel including sub-pixels with optical aperture parts being disposed ina matrix form in a first direction and a second direction that isroughly perpendicular to the first direction; and a light-ray controlmodule which is provided by opposing to the display panel forcontrolling light rays towards the first direction, wherein: each of theaperture parts of two of the sub-pixels neighboring to each other in thefirst direction includes an overlapping region overlapping with eachother in the second direction and an non-overlapping region notoverlapping with each other; provided that a width of the aperture partin the second direction is defined as a longitudinal aperture width, thenon-overlapping region includes an aperture width fluctuating regionwhere the longitudinal aperture width changes continuously from roughlya center of the aperture part towards both ends of the first direction,respectively; and a sum of the longitudinal aperture widths of the twooverlapping regions overlapping with each other located at a sameposition in the first direction is larger than the longitudinal aperturewidth in roughly the center of the aperture part.

As an exemplary advantage according to the invention, the presentinvention can achieve a fine stereoscopic display property even with anaked-eye type stereoscopic display device which employs a display panelwith narrow-pitch sub-pixels or a display panel with a large number ofpixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a fragmentary elevational view showing the structure ofExample 1 of a first exemplary embodiment, and FIG. 1B is a graphshowing the relation between positions in a first direction andlongitudinal aperture widths in Example 1 of the first exemplaryembodiment;

FIG. 2A is a fragmentary elevational view showing the structure ofExample 2 of the first exemplary embodiment, and FIG. 2B is a graphshowing the relation between positions in the first direction andlongitudinal aperture widths in Example 2 of the first exemplaryembodiment;

FIG. 3A is a fragmentary elevational view showing the structure ofExample 3 of the first exemplary embodiment, and FIG. 3B is a graphshowing the relation between positions in the first direction andlongitudinal aperture widths in Example 3 of the first exemplaryembodiment;

FIG. 4A is a fragmentary elevational view showing a case where cornersof the aperture parts of Example 1 of the first exemplary embodiment arerounded, and FIG. 4B is a graph showing the relation between positionsin the first direction and longitudinal aperture widths in the caseshown in FIG. 4A;

FIG. 5A is a fragmentary elevational view showing a case where overallcontraction is generated in the aperture part of Example 1 of the firstexemplary embodiment, and FIG. 5B is a graph showing the relationbetween positions in the first direction and longitudinal aperturewidths in the case shown in FIG. 5A;

FIG. 6 is a graph showing 3D moiré recognized by an observer in a casewhere the corner of the aperture part of Example 1 of the firstexemplary embodiment is rounded;

FIG. 7A is a graph showing the subjective evaluation result of 3D moiré,and FIG. 7B is an explanatory chart showing the way of calculating thelongitudinal aperture difference ratio;

FIG. 8A is a fragmentary elevational view showing the structure of asecond exemplary embodiment, and FIG. 8B is a graph showing the relationbetween positions in a first direction and longitudinal aperture widthsaccording to the second exemplary embodiment;

FIG. 9A is a fragmentary elevational view showing a case where cornersof the aperture parts in the second exemplary embodiment are rounded,and FIG. 9B is a graph showing the relation between positions in thefirst direction and longitudinal aperture widths in the case shown inFIG. 9A;

FIG. 10A is a fragmentary elevational view showing the structure ofComparative Example of a third exemplary embodiment, FIG. 10B is a firstgraph showing the relation between positions in a second direction andluminance in Comparative Example of the third exemplary embodiment, andFIG. 10C is a second graph showing the relation between positions in thesecond direction and luminance in Comparative Example of the thirdexemplary embodiment;

FIG. 11A is a fragmentary elevational view showing the structure ofExample 1 of the third exemplary embodiment, FIG. 11B is a first graphshowing the relation between positions in the second direction andluminance in Example 1 of the third exemplary embodiment, and FIG. 11Cis a second graph showing the relation between positions in the seconddirection and luminance in Example 1 of the third exemplary embodiment;

FIG. 12A is a fragmentary elevational view showing the structure ofExample 2 of the third exemplary embodiment, FIG. 12B is a first graphshowing the relation between positions in the second direction andluminance in Example 2 of the third exemplary embodiment, and FIG. 12Cis a second graph showing the relation between positions in the seconddirection and luminance in Example 2 of the third exemplary embodiment;

FIG. 13 is a detailed perspective view showing a stereoscopic displaydevice according to each Example of each exemplary embodiment;

FIG. 14 is a fragmentary plan view of the stereoscopic display deviceshown in FIG. 13 viewed from the above;

FIG. 15A is a fragmentary elevational view showing the structure of arelated technique, and FIG. 15B is a graph showing the relation betweenpositions in the first direction and longitudinal aperture widthsaccording to the related technique;

FIG. 16A is a fragmentary elevational view showing a case where cornersof the aperture parts in the related technique are rounded, and FIG. 16Bis a graph showing the relation between positions in the first directionand longitudinal aperture widths in the case shown in FIG. 16A;

FIG. 17 is a graph showing the relation regarding the angle θ of thecorner of an aperture part, a longitudinal aperture width change valueWq, and a longitudinal aperture width change section Vq in a case wherecorners of the aperture parts in the related technique are rounded;

FIG. 18 is a graph showing 3D moiré recognized by the observer in a casewhere the corners of the aperture parts in the related technique arerounded;

FIG. 19A is a fragmentary elevational view showing the structure ofExample 1 of a fourth exemplary embodiment, and FIG. 19B is a graphshowing the relation between positions in the first direction andlongitudinal aperture widths in Example 1 of the fourth exemplaryembodiment;

FIG. 20A is a fragmentary elevational view showing the structure ofExample 2 of the fourth exemplary embodiment, and FIG. 20B is a graphshowing the relation between positions in the first direction andlongitudinal aperture widths in Example 2 of the fourth exemplaryembodiment;

FIG. 21A is a fragmentary elevational view showing the structure ofExample 1 of a fifth exemplary embodiment, and FIG. 21B is a schematicchart showing initial alignment directions of liquid crystal insub-pixels of FIG. 21A, the electrode long-side directions, and theelectric field directions;

FIG. 22A is a schematic chart showing the relation between initialalignment direction of the positive liquid crystal and an electrode of asub-pixel A according to the fifth exemplary embodiment, FIG. 22B is aschematic chart showing the relation between initial alignment directionof the positive liquid crystal and an electrode of a sub-pixel Baccording to the fifth exemplary embodiment, FIG. 22C is a schematicchart showing liquid crystal molecules after a voltage is applied whenpositive liquid crystal is used in the fifth exemplary embodiment, FIG.22D is a schematic chart showing the relation between initial alignmentdirection of the negative liquid crystal and an electrode of thesub-pixel A according to the fifth exemplary embodiment, FIG. 22E is aschematic chart showing the relation between initial alignment directionof the negative liquid crystal and an electrode of the sub-pixel Baccording to the fifth exemplary embodiment, and FIG. 22F is a schematicchart showing liquid crystal molecules after a voltage is applied whenthe negative liquid crystal is used in the fifth exemplary embodiment;

FIG. 23A is a fragmentary elevational view showing the structure ofExample 2 of the fifth exemplary embodiment, and FIG. 23B is a schematicchart showing initial alignment directions of liquid crystal insub-pixels of FIG. 23A, the electrode long-side directions, and theelectric field directions;

FIG. 24A is a chart showing a first structural example of Example 3 ofthe fifth exemplary embodiment, FIG. 24B is a chart showing a secondstructural example of Example 3 of the fifth exemplary embodiment, andFIG. 24C is a chart showing a third structural example of Example 3 ofthe fifth exemplary embodiment;

FIG. 25A is a chart showing a first structural example of Example 4 ofthe fifth exemplary embodiment, and FIG. 25B is a chart showing a secondstructural example of Example 4 of the fifth exemplary embodiment; and

FIG. 26A is a chart showing a first structural example of Example 5 ofthe fifth exemplary embodiment, and FIG. 26B is a chart showing a secondstructural example of Example 5 of the fifth exemplary embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, modes (referred to as “exemplary embodiments” hereinafter)for embodying the present invention will be described by referring tothe accompanying drawings. Note that same reference numerals are usedfor substantially the same structural elements in current Specificationand the Drawings. Hatching in the drawings does not mean a cut sectionbut is applied for allowing those skilled in the art to comprehendeasily.

(Overall Structures)

The overall structures of a stereoscopic display device that is incommon to each exemplary embodiment and each Example according to thepresent invention will be described by referring to FIG. 13 and FIG. 14.As shown in FIG. 13, a stereoscopic display device 3 includes: a displaypanel 2 which is provided with sub-pixels (to be described later)including optical apertures, which are disposed in matrix along a firstdirection x and a second direction y that is roughly perpendicular tothe first direction x; and a lens 1 which is disposed by opposing to thedisplay panel 2 and function as a light-ray control module forcontrolling light rays towards the first direction x. The lens 1 isdisposed on the observer side of the display panel 2. The lens 1 and thedisplay panel 2 are illustrated by being separated from each other inFIG. 13 to be easily comprehended. In practice, however, the lens 1 andthe display panel 2 are used by being in contact with each other asshown in FIG. 14.

The stereoscopic display device 3 may be of any types as long as itincludes the display panel 2 on which the sub-pixels (to be describedlater) of the present invention are arranged in matrix. The displaypanel 2 may be a plasma display device or an organic EL display as aself-luminous type display device or a non-self-luminous type liquidcrystal display, for example. Further, as the lens 1 as the light-raycontrol module, a lenticular lens, a GRIN lens, a fly-eye lens, or thelike can be employed.

FIG. 14 is a plan view of a part of the stereoscopic display device 3shown in FIG. 13 viewed from the above. First-viewpoint sub-pixels 4 andsecond-viewpoint sub-pixels 5 are arranged in matrix on the displaypanel 2, and unit lenses of the lens 1 are disposed by corresponding tothe sub-pixel pairs. On the observing plane side, a first viewpointimage view field 6 and a second viewpoint image view field 7 are formed.It is not essential for the light-ray control module to be the lens 1 aslong as view fields of each viewpoint can be formed on the observingplane side. It is possible to employ a parallax barrier or a type withwhich the emission light itself has the directivity. While FIG. 14 showsthe 2-viewpoint stereoscopic display device 3, the present invention canbe applied to a multi-viewpoint type or an IP (integral photography)type stereoscopic display device through changing the pitch of thesub-pixels and the light-ray control modules, for example.

First Exemplary Embodiment (Example 1)

Example 1 of the first exemplary embodiment will be described byreferring to FIG. 1A. FIG. 1A shows three sub-pixels 100, 200, and 300disposed in parallel in the first direction x out of a great number ofsub-pixels disposed in matrix. That is, the sub-pixels 100, 200, and 300of Example 1 are arranged along the first direction x. The unit lensesof the lens 1 as the light-ray control modules are disposed at thepositions corresponding to a pair of sub-pixels 100, 300, and arrangedrepeatedly along the first direction x. Because of such structure, thefirst direction x is roughly in parallel to the observer viewpointdirection that is the light-separating direction.

Hereinafter, the sub-pixel 100 will be focused and described, while thereference numerals of the neighboring sub-pixels 200 and 300 will alsobe written in parenthesis as appropriate. Further, for those expressedwith L or R added in the end of the reference numerals, the referencenumerals alone by omitting L or R are used as the general terms thereof.For example, overlapping sections 101L and 101R can be expressed as theoverlapping section 101 as the general term. Such rules regarding thereference numerals are the same in each of other exemplary embodimentsand Examples.

First, the outline of Example 1 will be described. Respective apertureparts 110 (210, 310) of two sub-pixels 100 (200, 300) neighboring toeach other in the first direction x have overlapping regions 121 (221,321) which overlap with each other in a second direction y andnon-overlapping regions (aperture width fluctuating regions and aperturewidth constant regions to be described later) which do not overlap witheach other. Provided that the width in the second direction y of theaperture part 110 (210, 310) is defined as a longitudinal aperturewidth, the non-overlapping region include an aperture width fluctuatingregion 122 (222, 322) which continuously changes towards the both endsof the first direction x from roughly the center of the aperture part110 (210, 310). The sums of the longitudinal aperture widths of the twooverlapping regions 121 (221, 321) which overlap with each other at thesame position in the first direction x, “111L+211R” and “111R+311L”, arelarger than the longitudinal aperture widths 113 (223, 323) roughly inthe centers of the aperture parts 110 (210, 310).

The sums of the longitudinal aperture widths of the two overlappingregions 121 (221, 321) which overlap with each other at the sameposition on the first direction x, “111L+211W” and “111R+311L”, may bedefined to be same at any positions in the first direction x or may bedefined to be within a range that is over 1 time and equal to 1.12 timesor less of the longitudinal aperture widths 113 (213, 313) in roughlythe centers of the aperture parts 110 (210, 310). Defining thatperipheral sides of the aperture part 110 as aperture sides, all theaperture sides included in the aperture width fluctuating regions 122(222, 322) may not be in parallel to the aperture sides included in theoverlapping regions 121 (221, 321). Non-overlapping regions may includethe aperture width constant regions 123 (223, 323) where thelongitudinal aperture widths 113 (213, 313) are same at any positions inthe first direction x.

Hereinafter, Example 1 will be described in more details. The sub-pixel100 (200, 300) includes three sections, i.e., an aperture width constantsection 103 (203, 303), an overlapping section 101 (201, 301), and anaperture width fluctuating section 102 (202, 302) in the first directionx.

The aperture width constant region 123 (223, 323) exists in the aperturewidth constant section 103 (203, 303). In the aperture width constantregion 123 (223, 323), the longitudinal aperture width 113 (213, 313) ofthe aperture part 110 (210, 310) is constant in the first direction x.Note that the aperture part 110 and the aperture parts 210, 310 arearranged to be shifted from each other in terms of the positions in thesecond direction y, and each of the shapes are in a rotational symmetricrelation of 180 degrees with respect to each other.

The overlapping region 121 (221, 321) exists in the overlapping section101 (201, 301). In the overlapping region 121 (221, 321), the aperturepart 110 (210, 310) overlaps with each other in the second direction y.The aperture part 110 is adjacent to the two aperture pats 210 and 310in the first direction, so that there are two each of the overlappingsections 101 and the overlapping regions 121. Specifically, the twooverlapping regions 121L (221L, 321L) and 121R (221R, 321R) exist bycorresponding to the two overlapping sections 101L (201L, 301L) and 101R(201R, 301R) in the aperture part 110 (210, 310).

The overlapping section 101 is determined according to the relation withrespect to the aperture parts 210 and 310 neighboring to each other inthe first direction x. Thus, the overlapping section 101L and theoverlapping section 201R in the first direction x coincide with eachother, and the overlapping section 101R and the overlapping section 301Lcoincide with each other as well.

The shape of the overlapping region 121 of Example 1 is a right-angledtriangle. Further, the two overlapping regions 121L and 121R existingwithin a single aperture part 110 are in a relation of congruent andline symmetrical with each other. Furthermore, the positions of the twooverlapping regions 121L and 121R in the second direction y coincidewith each other. In the overlapping regions 121L and 121R, the aperturesides 100A and 100B opposing to the neighboring aperture parts 210 and310 are not in parallel to each other. This is the same for theoverlapping regions 221L, 221R, 321L, 321R and the aperture sides 200A,200B, 300A, and 300B.

The relations regarding the sums of the longitudinal aperture widths inthe overlapping sections are as follows. As shown in FIG. 1A, theoverlapping sections 101L and 201R coincide with each other in the firstdirection x. Further, the sum of the longitudinal aperture width 111L ofthe overlapping region 121L in the overlapping section 101L and thelongitudinal aperture width 211R of the overlapping region 221R in theoverlapping section 201R takes a constant value in the first directionx. Similarly, the sum of the longitudinal aperture width 111R and thelongitudinal aperture width 311L takes a constant value in the firstdirection x.

The sums of the longitudinal aperture widths “111L+211W” and “111R+311L”are desirable to be constant in terms of the manufacture stability.However, it is not essential for the sums to take a constant value. Aswill be referred in the explanation of a plot 001 shown in FIG. 1B, itis sufficient for the sums to be larger than the longitudinal aperturewidth 113 of the aperture width constant region 123.

The aperture width fluctuating region 122 (222, 322) exists in theaperture width fluctuating section 102 (202, 302). There are twoaperture width fluctuating regions 122 (222, 322) in a single aperturepart 110 (210, 310). Specifically, two aperture width fluctuatingregions 122L (222L, 322L) and 122R (222R, 322R) exist by correspondingto the two aperture width fluctuating sections 102L (202L, 302L) and102R (202R, 302R) in the first direction of the aperture part 110 (210,310). The aperture width fluctuating region 122 (222, 322) existsbetween the overlapping region 121 (221, 321) and the aperture widthconstant region 123 (223, 323).

In the aperture width fluctuating regions 122 (222, 322), thelongitudinal aperture width changes depending on the positions in thefirst direction x. The longitudinal aperture width continuouslyincreases from the aperture width constant region 123 (223, 323) towardsthe overlapping region 121 (221, 321), i.e., towards the both-end sidesof the aperture part 110 (210, 310). Specifically, the longitudinalaperture width of the aperture width fluctuating region 122L (222L,322L) becomes the minimum-value longitudinal aperture width 113 (213,313) at the position in contact with the aperture width constant region123 (223, 323), becomes the maximum-value longitudinal aperture width111 (211, 311) at the position in contact with the overlapping region121 (221, 321), and continuously and linearly increases from the minimumvalue to the maximum value at the positions between those. Note that theshape of the aperture width fluctuating region 122 (222, 322) in Example1 is an isosceles trapezoid.

The relation between the positions in the first direction and thelongitudinal aperture width in Example 1 is shown by the plot 001 ofFIG. 1B. The longitudinal aperture width is always constant in theaperture width constant section 103 (203, 303). Further, the sums of thelongitudinal aperture widths “111L+211W” and “111R+311L” of theoverlapping section 101 (201, 301) are always constant and each of thoseis a larger value than the longitudinal aperture width 113. In theaperture width fluctuating section 102 (202, 302) existing between theaperture width constant section 103 (203, 303) and the overlappingsection 101 (201, 301), the longitudinal aperture width changes as theposition in the first direction x changes. In Example 1, the shape ofthe aperture width fluctuating region 122 (222, 322) is an isoscelestrapezoid, so that the longitudinal aperture width changes in a linearform. Assuming that the range where the longitudinal aperture widthchanges in the first direction x is V1, there are the maximum value Whof the longitudinal aperture width and the minimum value Wl of thelongitudinal aperture width generated within the range V1. As describedabove, it is not essential for the sums of the longitudinal aperturewidths to be constant.

First Exemplary Embodiment (Example 2)

Example 2 of the first exemplary embodiment will be described byreferring to FIG. 2A. Sub-pixels 130, 230, and 330 of Example 2 arearranged along the first direction x. The unit lenses of the lens 1 asthe light-ray control modules are disposed at the positionscorresponding to a pair of sub-pixels 130, 330, and arranged repeatedlyalong the first direction x.

An aperture part 140 (240, 340) of the sub-pixel 130 (230, 330) ofExample 2 has three sections, i.e., an aperture width constant section133 (233, 333), an overlapping section 131 (231, 331), and an aperturewidth fluctuating section 132 (232, 332) in the first direction x.

Specifically, one aperture width constant section 133 (233, 333), twoaperture width fluctuating sections 132L (232L, 332L), 132R (232R,332R), and two overlapping sections 131L (231L, 331L), 131R (231R, 331R)exist in a single aperture part 140 (240, 340).

The shape of an aperture width constant region 153 (253, 353) isrectangular like the shape of the aperture width constant region 123(223, 323) in Example 1 shown in FIG. 1A. A feature of Example 2 is thatthe position of the aperture width constant region 153 of the aperturepart 140 in the second direction y and the positions of the aperturewidth constant regions 253, 353 of the neighboring aperture parts 240,340 in the second direction y coincide with each other.

The overlapping regions 151L and 151R of the aperture part 140 are bothin a right-angled triangle shape and are in a relation of congruent androtational symmetric with each other. Further, the overlapping regionsof different aperture parts whose positions on the first direction xcoincide with each other, e.g., the overlapping region 151L and theoverlapping region 251R, are also in a relation of congruent androtational symmetric with each other. Further, the positions of the twooverlapping regions 151L and 151R of the aperture part 140 in the seconddirection y are shifted from each other. This point is a feature that isdifferent from that of the aperture part 110 of Example 1 shown in FIG.1A.

Out of the aperture sides which define the shape of the aperture part140 within the overlapping regions 151L, 151R, the aperture sides 130A,130B disposed by opposing to the aperture parts 240, 340 neighboring toeach other in the first direction x are in parallel to each other.Further, each of the aperture sides 130A and 130B is in parallel to noneof the other aperture sides which define the shape of the aperture part140. From another viewpoint, the aperture sides of the aperture widthfluctuating regions 152L, 152R are in parallel to none of the aperturesides in the overlapping regions 151L, 151R. This is the same in theaperture part 110 of Example 1 shown in FIG. 1A. Described above is alsothe same for the overlapping regions 251L, 251R, 351L, 351R and theaperture sides 230A, 230B, 330A, and 330B.

The shape of the aperture width fluctuating regions 152L and 152R of theaperture part 140 is a trapezoid. The lower bases of those trapezoidsare disposed on both sides of the aperture part 140 in the firstdirection x, respectively. Thereby, the longitudinal aperture width atthe positions in the first direction x continuously and linearlyincreases towards the both-end sides from roughly the center of theaperture part 140 as in the case of Example 1 of FIG. 1 A. While theshape of the aperture width fluctuating regions 122L, 122R in Example 1of FIG. 1A is an isosceles trapezoid, the shape of the aperture widthfluctuating regions 152L, 152R in Example 2 is not limited to anisosceles trapezoid. Described above is also the same for the aperturewidth fluctuating regions 252L, 252R, 352L, and 352R.

In Example 2, there is also a following feature in the layout method ofthe aperture parts of the sub-pixels. In FIG. 2A, the aperture parts140, 240, and 340 neighboring to each other in the first direction x aredisposed in such a manner that the positions thereof in the seconddirection y are all become the same. Further, the aperture part 140 andthe aperture parts 240, 340 neighboring to that are congruent to eachother.

FIG. 2B is a graph showing the relation between the positions in thefirst direction x and the longitudinal aperture width of Example 2 by aplot 031. In Example 2, the shape of the aperture part of the sub-pixelis different from that of Example 1. However, the same relation as thecase of the plot 001 of Example 1 shown in FIG. 1B can be satisfied.Other structures of Example 2 are same as those of Example 1.

First Exemplary Embodiment (Example 3)

Example 3 of the first exemplary embodiment will be described byreferring to FIG. 3A. Sub-pixels 160, 260, and 360 of Example 3 arearranged along the first direction x. The unit lenses of the lens 1 asthe light-ray control modules are disposed at the positionscorresponding to a pair of sub-pixels 160, 360, and arranged repeatedlyalong the first direction x.

An aperture part 170 (270, 370) of the sub-pixel 160 (260, 360) ofExample 3 has three sections, i.e., an aperture width constant section163 (263, 363), an overlapping section 161 (261, 361), and an aperturewidth fluctuating section 162 (262, 362) in the first direction x.Specifically, one aperture width constant section 163 (263, 363), twoaperture width fluctuating sections 162L (262L, 362L), 162R (262R,362R), and two overlapping sections 161L (261L, 361L), 161R (261R, 361R)exist in a single aperture part 170 (270, 370).

In the aperture width constant section 163, the aperture sides 160C and160C′ for defining the shape of the aperture part 170 are both bent. Thetwo aperture sides 160C and 160C′ both are in a relation of translationalong the second direction y, so that the longitudinal aperture widthwithin the aperture width constant section 163 is maintained constant inthe first direction x. This is the same also for the aperture sides260C, 260C′ and the aperture sides 360C, 360C′.

In the overlapping section 161L, the aperture side 160F′ for definingthe shape of the aperture part 170 is bent. The aperture side 160F′ andthe aperture side 260F of the overlapping section 261R that is same asthe overlapping section 161L are in a relation of translation along thesecond direction y. This is a relation in which the border line betweenthe aperture part 170 and the aperture part 270 neighboring thereto havea constant width in the first direction x, and the sums of thelongitudinal aperture widths in the overlapping sections 161L, 261Rbecome constant in the first direction x. This is the same in theaperture sides 160F, 360F′ in the respective same overlapping sections161R, 361L. Note that it is desirable for the sums of the longitudinalaperture widths in the same overlapping sections 161L, 261R to beconstant in the first direction x. However, it is not essential for thesums to be constant as in the case of Example 1. That is, the apertureside 160F′ and the aperture side 260F may not have to be in a relationof translation along the second direction y.

In the sub-pixel shown in FIG. 3A, the overlapping region 181L (181R)and the overlapping region 281R (381L) in the same overlapping section161L (161R) are not congruent with each other. This is because theaperture side 160F′ (160F) and the aperture side 260F (360F′) are in arelation of translation as described above.

The aperture sides 160D (160E) and 160D′ (160E′) in the aperture widthfluctuating section 162L (162R) for defining the shape of the aperturepart 170 are both bent. In this case, the longitudinal aperture width ofthe aperture width fluctuating region 182L (182R) changes continuouslyand non-linearly towards the overlapping region 181L (181R) from theaperture width constant region 183.

FIG. 3B is a graph showing the relation between the positions in thefirst direction x and the longitudinal aperture widths of Example 3 by aplot 061. As in the cases of Examples 1 and 2, the longitudinal aperturewidth also changes continuously towards the both-end sides of theaperture part in the first direction in Example 3. However, in Example3, the bent aperture sides described above are used. Thus, it isdifferent from Examples 1 and 2 in respect that the longitudinalaperture width changes non-linearly (curvilinearly) in the range V1where the longitudinal aperture width changes. Other structures ofExample 3 are the same as those of Examples 1 and 2.

First Exemplary Embodiment (Operations and Effects)

Examples 1 to 3 described above employ the ideal sub-pixel structures. Acase where a rounded corner is generated in the aperture part in Example1 will be described by referring to FIG. 4A. In FIG. 4A, shown are theaperture parts 110, 210 (broken lines) of the ideal sub-pixels shown inFIG. 1A and the aperture parts 110 a, 210 a of the sub-pixels 100 a, 200a with the rounded corners. As in the case of the ideal aperture part110 (210), there are three sections, i.e., the aperture width constantsection 103 a (203 a), the aperture width fluctuating section 102 aL(202 aR), and the overlapping section 101 aL (201 aR) in the aperturepart 110 a (210 a).

Compared to the ideal aperture part 110 (210), the overlapping section101 aL (201 aR) in the aperture part 110 a (210 a) is reduced due torounding of the corner and, at the same time, the aperture widthfluctuating section 102 aL (202 aR) is expanded for that. FIG. 4B showsthe state where the total value of the longitudinal aperture widthschanges thereby for the first direction x. In the ideal aperture part110 (210), the longitudinal aperture width changes continuously from theaperture width fluctuating section to the overlapping section. In themeantime, in the aperture part 110 a (210 a) with the rounded corner,there is a point at which the longitudinal aperture width becomesradically decreased in the vicinity of the overlapping section 101 aL(201 aR) within the aperture width fluctuating section 102 aL (202 aR).Therefore, it is expressed by the plot 001 a in which the longitudinalaperture width in the aperture width fluctuating region 122 aL (222 aR)increases continuously from the aperture width constant region 123 a(223 a) towards the overlapping region 121 aL (221 aR), drops by theamount of the longitudinal aperture width change value Wq in thelongitudinal aperture width change section Vq in the vicinity of theoverlapping region 121 aL, and increases again.

The plot 001 a shown in FIG. 4B shows the relation of the longitudinalaperture width with respect to the first direction x. As can be seenfrom that, the longitudinal aperture width change value Wq is generatedin the longitudinal aperture width change section Vq due to the roundedcorner. However, the longitudinal aperture width change value Wq is asmaller value than Wh−Wl that is the difference between the sum of thelongitudinal aperture widths 111 aL (211 aR), “111 aL+211 aR”, in theoverlapping section 101 aL (201 aR) and the longitudinal aperture width113 a (213 a) in the aperture width constant section 123 a (223 a). Thatis, a relation of Wq<Wh−Wl applies. The phenomenon shown in FIG. 4A andFIG. 4B is also found in the case where rounded corners are generated inthe aperture parts of Example 2 and Example 3.

Further, a case where the aperture part is reduced as a whole due tovariation in the processing precision will be described by referring toFIG. 5A. FIG. 5A shows the aperture parts 110, 210 (broken lines) of theideal sub-pixels shown in FIG. 1A and the aperture parts 110 b, 210 b ofthe sub-pixels 100 b, 200 b reduced as a whole due to variation of theprocessing precision. As in the case of the ideal aperture part 110(210), there are three sections, i.e., the aperture width constantsection 103 b (203 b), the aperture width fluctuating section 102 bL(202 bR), and the overlapping section 101 bL (201 bR) in the aperturepart 110 b (210 b). The aperture width constant section 103 b (203 b)corresponds to the aperture width constant region 123 b (223 b) and thelongitudinal aperture width 113 b (213 b).

Compared to the ideal aperture part 110 (210), in the aperture part 110b (210 b), the overlapping section 101 bL (201 bR) is reduced due toreduction as a whole and, at the same time, the aperture widthfluctuating section 102 bL (202 bR) is expanded for that. FIG. 5B showsthe state where the total value of the longitudinal aperture widthschanges thereby for the first direction x. Looking at the firstdirection x from the origin towards the positive direction, in the idealaperture part 110 (210) shown by the plot 001, the longitudinal aperturewidth in the aperture width fluctuating section 122 bR (222 bR)increases continuously from the border line between the aperture widthconstant section 103 (203) and the aperture width fluctuating section102L (202R) to the overlapping section 101L (201R) and becomes constantin the overlapping section 101L (201R). In the meantime, in the aperturepart 110 b (210 b) reduced as a whole shown by a plot 001 b, thelongitudinal aperture widths become decreased uniformly. Thus, thelongitudinal aperture width in the aperture width fluctuating section102 bL (202 bL) increases continuously from the minimum value Wl to themaximum value Wh and drops by the amount of the longitudinal aperturewidth change value Wr in the longitudinal aperture width change sectionVq in the vicinity of the overlapping region 121 bL (221 bR). Further,the longitudinal aperture width in the overlapping section 101 bL (201bR) also remains decreased for the amount of the longitudinal aperturewidth change value Wr.

As described, in the plot 001 b shown in FIG. 5B, the longitudinalaperture widths in the aperture width fluctuating section 102 bL (202bR) and the overlapping section 101 bL (201 bR) are larger value thanthe minimum value Wl that is the longitudinal aperture width of theaperture width constant section 103 b (203 b) as in the case of the plot001 a that is the case of the rounded corner shown in FIG. 4B. Thephenomenon shown in FIG. 5A and FIG. 5B is also found in the case wherethe aperture part is reduced as a whole in Example 2 and Example 3.

FIG. 1A to FIG. 5B will be described roughly. In all the drawings, thelongitudinal aperture width in the aperture width constant sectionlocated roughly at the center of the aperture part is smaller than thelongitudinal aperture widths in the other sections (the sum of thelongitudinal aperture widths in the overlapping sections), which is theminimum value Wl. Considering it in terms of the image luminanceprojected on the observing plane, the image luminance projected atroughly the center of the stereopsis region on the observing plane sideis always lower than the image luminance at other observing angles.Thus, when the observing position is shifted from the normalstereoscopic observing position, white moiré is generated at all times.

More specifically, it can be described as follows. FIG. 6 shows an imageof 3D moiré in the state of FIG. 4B. The lateral axis of FIG. 6 is theobserving angles from the position along the first direction, and thelongitudinal axis is the luminance distribution for the observingangles. Dotted lines show the luminance distributions when an image isoutputted to only one of the pixels in a case where a sub-pixel 100 isdefined as the right-eye pixel and a sub-pixel 300 is defined as theleft-eye pixel. The luminance distribution Y1 is presented in a casewhere white is displayed on the right-eye pixel and black is displayedon the left-eye pixel, the luminance distribution Y2 is presented in acase where black is displayed on the right-eye pixel and white isdisplayed on the left-eye pixel, and the luminance distribution Y3 ispresented in a case where white is displayed on the both pixels.Basically, the relation regarding the luminance can be expressed asY3=Y1+Y2. In FIG. 6, the plot 001 a shown in FIG. 4B is also shown in asuperimposed manner.

Note here that the right-eye observing region is 810R, and the left-eyeobserving region is 810L. As shown in FIG. 6, Wh−Wl>Wq described aboveapplies even in a case where both eyes of the observer are located inthe vicinity of the borders (e.g., positions T, S) of each of theobserving regions. Thereby, black moiré can be suppressed.

Further, the expression “continuously changes” regarding the change inthe longitudinal aperture width in the aperture width fluctuating regionmeans that a single value of the longitudinal aperture width is decidedfor the position in a given first direction and the value of thelongitudinal aperture width changes without a break for changes in thepositions in the first direction. When the longitudinal aperture widthchanges continuously, the change in the image luminance projected on theobserving plane becomes continuous so that a fine stereoscopic displaycan be achieved. It is desirable for the longitudinal aperture widthwith respect to the positions in the first direction to change smoothlyfor the first direction to be able to differentiate. In a case where therounding of the corners of the aperture part and the overall changes inthe aperture part are small, the longitudinal aperture width changesection Vq becomes extremely small. Therefore, it is considered that thelongitudinal aperture width in FIG. 4B and FIG. 5B also increasescontinuously from the aperture width constant region 123 a (223 a)towards the vicinity of the overlapping region 121 aL (221 aL).

The stereoscopic display quality perceived by observers was evaluated byusing typical evaluation images in a case where white moiré wasgenerated and a case where black moiré was generated when observingstereoscopic display. FIG. 7A and FIG. 7B shows the results thereof. InFIG. 7A, the lateral axis shows the longitudinal aperture differenceratio “(Wh−Wl)/Wl, and the longitudinal axis shows the subjective level.As shown in FIG. 7B, the maximum value Wh is the sum “L1+L2” of thelongitudinal aperture widths in the overlapping region, and the minimumvalue Wl is the longitudinal aperture width L in the aperture widthconstant region. The subjective levels were set to be in five levels.Score 5 is the best image quality, score 3 is an allowable imagequality, and score 1 is the most unacceptable image quality. FIG. 7Ashows the average of the scores of ten examinees and the standarddeviation. The positive region on the lateral axis shows a region wherewhite moiré is generated, and the negative region shows a region whereblack moiré is generated. According to the evaluation, it is found thatthe region of the white moiré has the wider region that is subjectivelyallowable. Further, it is also found that the subjectively allowablerange is the range of −4% to 12% as the value of the longitudinalaperture difference ratio.

From the result shown in FIG. 7A, followings can be said regarding therelation of the sum of the longitudinal aperture width in the aperturewidth constant region and the longitudinal aperture width in theoverlapping region. The allowable range is the range where the value ofthe longitudinal aperture difference ratio is 12% or less so that it isdesirable for the sum of the longitudinal aperture widths in theoverlapping region to be in a range of exceeding 1 time and equal to orless than 1.12 times of the longitudinal aperture width of the aperturewidth constant region for not allowing black moiré.

Further, followings can be said from the results of FIG. 7. In therelated techniques, when there is variation in the processing precisiongenerated for the ideal sub-pixel structure, black moiré is generatednecessarily. Thus, the subjectively allowable range of the observer isnarrow. In the meantime, the first exemplary embodiment is designed tosuppress black moiré and intentionally generate white moiré at the sametime even when there is variation generated in the processing precisionfor the ideal sub-pixel structure, so that the allowable range of theobserver becomes wider compared to that of the related technique. Thismakes it possible to achieve a more dominantly fine stereoscopic displayproperty with a naked-eye type stereoscopic display device which employsa display panel having narrow-pitch sub-pixels for achieving highdefinition and a display panel with a large number of pixels.

Second Exemplary Embodiment

A second exemplary embodiment will be described by referring to FIG. 8A.Sub-pixels 600, 700, and 800 of the second exemplary embodiment arearranged along the first direction x. The unit lenses of the lens 1 asthe light-ray control modules are disposed at the positionscorresponding to a pair of sub-pixels 600, 800, and arranged repeatedlyalong the first direction x.

The aperture width constant region existed in the first exemplaryembodiment does not exist in the aperture part 610 (710, 810) of thesub-pixel 600 (700, 800) of the second exemplary embodiment. There aretwo overlapping regions 621L (721L, 821L) and 621R (721R, 821R) in theaperture part 610 (710, 810). Further, there is an aperture widthfluctuating region existing between the two overlapping regions. Theaperture width fluctuating region is divided into two aperture widthfluctuating regions 622L (722L, 822L) and 622R (722R, 822R).

That is, the aperture part 610 includes: the overlapping region 621(621L, 621R) of the overlapping section 601 (601L, 601R); and theaperture width fluctuating region 622 (622L, 622R) of the aperture widthfluctuating section 602 (602L, 602R). The aperture part 710 includes:the overlapping region 721 (721L, 721R) of the overlapping section 701(701L, 701R); and the aperture width fluctuating region 722 (722L, 722R)of the aperture width fluctuating section 702 (702L, 702R). The aperturepart 810 includes: the overlapping region 821 (821L, 821R) of theoverlapping section 801 (801L, 801R); and the aperture width fluctuatingregion 822 (822L, 822R) of the aperture width fluctuating section 802(802L, 802R). The longitudinal aperture width 611 (611L, 611R)corresponds to the overlapping region 621 (621L, 621R), the longitudinalaperture width 711 (711L, 711R) corresponds to the overlapping region721 (721L, 721R), and the longitudinal aperture width 811 (811L, 811R)corresponds to the overlapping region 821 (821L, 821R).

FIG. 8B shows the relation between the positions in the first directionx and the longitudinal aperture widths in the structure shown in FIG. 8Aas a plot 003. Within the range V1 where the longitudinal aperture widthchanges, the longitudinal aperture width changes continuously andlinearly from the minimum value Wl to the maximum value Wh.

FIG. 9A shows the state where the corner is rounded in the idealsub-pixel structure shown in FIG. 8A in the second exemplary embodiment.The aperture part 610 a of the sub-pixel 600 a with the rounded cornerincludes the overlapping region 621 aL of the overlapping section 601aL, and the aperture width fluctuating region 622 aL of the aperturewidth fluctuating section 602 aL. Similarly, the aperture part 701 a ofthe sub-pixel 700 a with the rounded corner includes the overlappingregion 721 aR of the overlapping section 701 aR, and the aperture widthfluctuating region 722 aR of the aperture width fluctuating section 702aR. The sum of the longitudinal aperture width 611 aL of the overlappingregion 621 aL and the longitudinal aperture width 711 aR of theoverlapping region 721 aR is the same at any positions in the firstdirection x.

FIG. 9B shows the relation between the positions in the first directionx and the longitudinal aperture widths in the structure shown in FIG. 9Aas a plot 003 a. In the second exemplary embodiment, the longitudinalaperture width change value Wq is generated in the longitudinal aperturechange section Vq due to the rounding of the corners as in the case ofthe first exemplary embodiment. However, a relation of Wh−Wl>Wq alsoapplies as in the case of the first exemplary embodiment. Therefore,even when there is variation generated in the processing precision forthe ideal sub-pixel structure, since the second exemplary embodiment isalso designed to suppress black moiré and intentionally generate whitemoiré at the same time, so that the allowable range of the observerbecomes wider compared to that of the related technique.

As shown in FIG. 8A, the point that none of the aperture sides fordefining the shape of the aperture part 610 (710, 810) in the aperturewidth fluctuating region 622 (722, 822) is not in parallel to theaperture sides for defining the shape of the aperture part 610 (710,810) in the overlapping region 621 (721, 821) is the same as the case ofthe first exemplary embodiment. Further, other structures, operations,and effects of the second exemplary embodiment are the same as those ofthe first exemplary embodiment.

Third Exemplary Embodiment (Comparative Example)

Before describing Examples of a third exemplary embodiment, ComparativeExample is first shown in FIG. 10A. Respective aperture parts 901UL,901DL, 901UR, and 901DR of sub-pixels 900UL, 900DL, 900UR, and 900DR ofComparative Example are in a same shape as the aperture part of Example1 of the first exemplary embodiment, and are disposed in a matrix formof 2×2. The unit lenses of the lens 1 as the light-ray control modulesare disposed at the positions corresponding to a pair of sub-pixels900UL (900DL), 900UR (900DR), and arranged repeatedly along the firstdirection x. FIG. 10B is a graph showing the change in the luminancedistribution for the second direction y in the aperture parts 901UL and901DL as a plot 902L. Similarly, FIG. 10C is a graph showing the changein the luminance distribution for the second direction y in the apertureparts 901UR and 901DR as a plot 902R.

The aperture parts 901UL, 901UR are disposed by being shifted from eachother in the second direction y and the aperture parts 901DL, 901DR aredisposed by being shifted from each other in the second direction y, sothat there is a difference generated in the maximum values of thechanges in the luminance distributions in the second direction y betweenthe plot 902L and the plot 902R. The lens 1 cannot distribute the lightrays to the second direction y, so that different luminancedistributions for the second direction y are projected in that state tothe observing plane. As a result, a sense of granularity is to beperceived in the image.

Third Exemplary Embodiment (Example 1)

FIG. 11A shows sub-pixels 910UL, 910DL, 910UR, and 910DR as Example 1 ofa third exemplary embodiment. Respective aperture parts 911UL, 911DL,911UR, and 911DR of the sub-pixels 910UL, 910DL, 910UR, and 910DR are ina shape acquired by expanding the shape of the aperture part ofComparative Example described above in the second direction y, and aredisposed in a matrix form of 2×2. The unit lenses of the lens 1 as thelight-ray control modules are disposed at the positions corresponding toa pair of sub-pixels 910UL (910DL), 910UR (910DR), and arrangedrepeatedly along the first direction x. The aperture part 911UR includesthe overlapping region 916 (916L, 916R), the aperture width fluctuatingregion 917 (917L, 917R), and the aperture width constant region 918. Theother aperture parts 911UL, 911DL, and 911DR also have the respectiveoverlapping regions, aperture width fluctuating regions, and theaperture width constant regions.

FIG. 11B is a graph showing the change in the luminance distribution forthe second direction y in the aperture parts 911UL and 911DL as a plot912L. Similarly, FIG. 11C is a graph showing the change in the luminancedistribution for the second direction y in the aperture parts 911UR and911DR as a plot 912R. Unlike Comparative Example (FIG. 10B and FIG.10C), there is almost no difference generated in the maximum values inthe changes of the luminance distributions in the second direction ywith Example 1. Therefore, with Example 1, the luminanceincrease/decrease generated at different positions in the viewpointdirection of the observing plane becomes almost the same. As a result, asense of granularity can be suppressed.

Third Exemplary Embodiment (Example 2)

FIG. 12A shows sub-pixels 920UL, 920DL, 920UR, and 920DR as Example 2 ofthe third exemplary embodiment. Respective aperture parts 921UL, 921DL,921UR, and 921DR of the sub-pixels 920UL, 920DL, 920UR, and 920DR are ina shape acquired by expanding a shape different from the aperture partof Example 1 described above in the second direction y, and are disposedin a matrix form of 2×2. The unit lenses of the lens 1 as the light-raycontrol modules are disposed at the positions corresponding to a pair ofsub-pixels 920UL (920DL), 920UR (920DR), and arranged repeatedly alongthe first direction x. The aperture part 921UR includes the overlappingregion 926 (926L, 926R), the aperture width fluctuating region 927(927L, 927R), and the aperture width constant region 928. The otheraperture parts 921UL, 921DL, and 921DR also have the respectiveoverlapping regions, aperture width fluctuating regions, and theaperture width constant regions.

FIG. 12B is a graph showing the change in the luminance distribution forthe second direction y in the aperture parts 921UL and 921DL as a plot922L. Similarly, FIG. 12C is a graph showing the change in the luminancedistribution for the second direction y in the aperture parts 921UR and921DR as a plot 922R. Unlike Comparative Example (FIG. 10B and FIG.10C), there is almost no difference generated in the maximum values inthe changes of the luminance distributions in the second direction ywith Example 2. Therefore, with Example 2, the luminanceincrease/decrease generated at different positions in the viewpointdirection of the observing plane becomes almost the same. As a result, asense of granularity can be suppressed.

Third Exemplary Embodiment (Summary)

Note here that the distance between the maximum value and the minimumvalue of the aperture position in the second direction of a singlesub-pixel is defined as an optical longitudinal aperture section. Thatis, the maximum value of the difference between the position at one endof the aperture part in the second direction and the position at theother end of the aperture part in the second direction is defined as“longitudinal aperture section”. In the aperture part 901UL ofComparative Example shown in FIG. 10A, the difference between theposition at one end 904 in the second direction y and the position atthe other end 905 in the second direction y is the longitudinal aperturesection 903. In the aperture part 911UL of Example 1 shown in FIG. 11A,the difference between the position at one end 914 in the seconddirection y and the position at the other end 915 in the seconddirection y is the longitudinal aperture section 913. In the aperturepart 921UL of Example 2 shown in FIG. 12A, the difference between theposition at one end 924 in the second direction y and the position atthe other end 925 in the second direction y is the longitudinal aperturesection 923. Further, as in the cases of the first and second exemplaryembodiments, the width of the aperture part in the longitudinaldirection is defined as “longitudinal aperture width”.

The sub-pixel according to the third exemplary embodiment has followingfeatures. In Comparative Example shown in FIG. 10A, the value of thelongitudinal aperture section 903 and the value of the largestlongitudinal aperture width among the longitudinal aperture widths atarbitrary positions in the first direction x are the same. In themeantime, in Example 1 shown in FIG. 11A, the value of the longitudinalaperture section 913 is larger than the value of the largestlongitudinal aperture width among the longitudinal aperture widths atarbitrary positions in the first direction x, and the positions of thelongitudinal aperture sections 913 in the second direction y coincidewith each other between the longitudinal aperture sections neighboringto each other in the first direction x. Similarly, in Example 2 shown inFIG. 12A, the value of the longitudinal aperture section 923 is largerthan the value of the largest longitudinal aperture width among thelongitudinal aperture widths at arbitrary positions in the firstdirection x, and the positions of the longitudinal aperture sections 923in the second direction y coincide with each other between thelongitudinal aperture sections neighboring to each other in the firstdirection x. This makes it possible with the third exemplary embodimentto suppress a sense of granularity perceived in images on the observingplane.

The third exemplary embodiment can also be expressed as follows. InExample 1 shown in FIG. 11A, the difference between the position at oneend of the aperture part 911UL in the second direction y and theposition at the other end of the aperture part 911UL in the seconddirection y becomes the maximum between the one end 914 and the otherend 915. The region of the maximum value is defined as the longitudinalaperture section 913. In that case, the longitudinal aperture section913 takes the value larger than the maximum value of the longitudinalaperture width of the aperture part 911UL. Further, the positions of oneend 914 and the other end 915 in the second direction y constituting thelongitudinal aperture section 913 are the same in the aperture parts911UL and 911UR which are neighboring to each other in the firstdirection x. This is the same in Example 2 shown in FIG. 12A.

In the cases of the aperture parts shown in FIG. 2A, FIG. 3A, and FIG.8A, the third exemplary embodiment can also be employed in the samemanner. Further, the point that none of the aperture sides for definingthe shape of the aperture part 911UR (921UR) in the aperture widthfluctuating region 917 (927) is in parallel to the aperture sides fordefining the shape of the aperture part 911UR (921UR) in the overlappingregion 916 (926) is the same as the cases of the first and secondexemplary embodiment. Further, other structures, operations, and effectsof the third exemplary embodiment are same as those of the first andsecond exemplary embodiments.

Fourth Exemplary Embodiment (Example 1)

Example 1 of a fourth exemplary embodiment will be described byreferring to FIG. 19A and FIG. 19B. FIG. 19A shows three sub-pixels1100, 1200, and 1300 disposed in parallel in the first direction x amonga great number of sub-pixels arranged in matrix. That is, the sub-pixels1100, 1200, and 1300 according to Example 1 are arranged along the firstdirection x. The unit lenses of the lens 1 as the light-ray controlmodules are disposed at the positions corresponding to a pair ofsub-pixels 1100, 1300, and such structure is arranged repeatedly alongthe first direction x. Thus, the first direction x is roughly inparallel to the viewpoint direction of the observer that is thelight-ray separating direction. Further, the aperture shape of the threesub-pixels 1100, 1200, and 1300 is an isosceles trapezoid, and thoseneighboring to each other are disposed by shifting the positions thereofin the second direction and in a rotationally symmetrical manner by 180degrees.

Each of the aperture parts 1110 (1210, 1310) of the two sub-pixels 1100(1200, 1300) neighboring to each other in the first direction xincludes: an overlapping region A1121 (1221, 1321), an overlappingregion B1125 (1225, 1325), and an overlapping region C1126 (1226, 1326)which overlap with each other in the second direction y; and an aperturewidth constant region 1123 (1223, 1323) which does not overlap with eachother (a non-overlapping region). The overlapping regions are generatedby overlap of the neighboring sub-pixels in the first direction x, sothat there are one each of those regions existing at both ends within asingle sub-pixel. The overlapping regions B and C are the longitudinalaperture width sum fluctuating regions. In the non-overlapping region,the longitudinal aperture width 1113 (1213, 1313) is always constantregardless of the positions in the first direction x. In this respect,Example 1 is different from the first and second exemplary embodiments.

Each of the sections in the first direction x is as follows. Theoverlapping sections A1101L, 1101R of the sub-pixel 1100 are the samesections with the overlapping section A1201R of the sub-pixel 1200 andthe overlapping section A1301L of the sub-pixel 1300, respectively.Further, the overlapping sections B1105L, 1105R of the sub-pixel 1100correspond to the overlapping section C1206R of the sub-pixel 1200 andthe overlapping section C1306L of the sub-pixel 1300, and theoverlapping sections C1106L, 1106R of the sub-pixel 1100 correspond tothe overlapping section B1205R of the sub-pixel 1200 and the overlappingsection B1305L of the sub-pixel 1300. Each of the sub-pixels in thosesections overlaps with each other in the second direction y and form theoverlapping regions A, B, and C.

The sums of the longitudinal aperture width and the longitudinalaperture width are as follows. The sum of the longitudinal aperturewidths of the overlapping section A1101L (1201R) of the sub-pixel 1100,“1111L+1211R”, is constant regardless of the positions in the firstdirection x. In the meantime, the sum of the longitudinal aperturewidths of the overlapping section B1105L (1206R) of the sub-pixel 1100,“1115L+1216R”, and the sum of the longitudinal aperture widths of theoverlapping section C1106L (1205R) of the sub-pixel 1100, “1116L+1215R”,fluctuate depending on the positions in the first direction x. This isbecause the longitudinal aperture width 1216R of the sub-pixel 1200fluctuates in the overlapping section B1105L depending on the positionsin the first direction x, and the longitudinal aperture width 1116L ofthe sub-pixel 1100 fluctuates in the overlapping section C1106Ldepending on the positions in the first direction x. Similarly, in theoverlapping section A1101R, the overlapping section B1105R, and theoverlapping section C1106R of the sub-pixel 1100, the sum of thelongitudinal aperture widths “1111R+1311L” is constant regardless of thepositions in the first direction x, while the sums of the longitudinalaperture widths “1115R+1316L” and “1116R+1315L” fluctuate depending onthe positions in the first direction x. The longitudinal aperture width1113 of the aperture width constant section 1103 of the sub-pixel 1100is constant regardless of the positions in the first direction x.Further, the other sub-pixels 1200 and 1300 have the relations similarto the case of the sub-pixel 1100.

The relations regarding the values of the sums of the longitudinalaperture widths are as follows. The sum of the longitudinal aperturewidths of the overlapping section A1101L of the sub-pixel 1100,“1111L+1211R”, the sum of the longitudinal widths of the overlappingsection B1105L, “1115L+1216R” and the sum of the longitudinal widths ofthe overlapping section C1106L, “1116L+1215R”, are larger than thelongitudinal aperture width “1113” of the aperture width constantsection 1103 regardless of the positions in the first direction x. Suchrelations are the same also for the sum of the longitudinal aperturewidths of the overlapping section A1101R of the sub-pixel 1100,“1111R+1311L”, the sum of the longitudinal widths of the overlappingsection B1105R, “1115R+1316L” and the sum of the longitudinal widths ofthe overlapping section C1106R, “1116R+1315L”. Further, the othersub-pixels 1200 and 1300 also have the relations similar to the case ofthe sub-pixel 1100.

The difference of Example 1 with respect to the first and secondexemplary embodiments is as follows. As in the cases of the first andsecond exemplary embodiments, the sub-pixel in Example 1 has anoverlapping section that is overlapped in the second direction y for thesub-pixel neighboring thereto in the first direction x. In the first andsecond exemplary embodiment, the sum of the longitudinal aperture widthsin the overlapping section is constant regardless of the positions inthe first direction x. In the meantime, in Example 1, the overlappingsection is divided into three sections A, B, and C, the sum of thelongitudinal aperture widths is constant only in the overlapping sectionA that is roughly in the center of the overlapping section, and the sumof the longitudinal aperture widths fluctuates in the overlappingsections B and C existing at both ends of the overlapping section A.This is because the opposing aperture sides of the sub-pixel 1100 andthe neighboring sub-pixel 1200 are disposed by being shifted in thefirst direction x. Specifically, a corner part 1100 p of the sub-pixel1100 and a corner part 1200 q of the sub-pixel 1200 are shifted in thefirst direction x. Similarly, a corner part 1100 q of the sub-pixel 1100and a corner part 1200 p of the sub-pixel 1200 are shifted in the firstdirection x.

In those overlapping sections B and C, the sum of the longitudinalaperture widths changes continuously and linearly. This is the samebehavior as that of the longitudinal aperture widths in the aperturewidth fluctuating sections of the first and second exemplaryembodiments.

The relation between the positions in the first direction x and thelongitudinal aperture widths in Example 1 is shown by a plot 041 in FIG.19B. In the aperture width constant section 1103 (1203, 1303), thelongitudinal aperture width is always constant. Further, the sum of thelongitudinal aperture widths in the overlapping section A1101 (1201,1301) is always constant regardless of the positions in the firstdirection x, and it is a larger value than the longitudinal aperturewidth in the aperture width constant section 1103 (1203, 1303). In theoverlapping section B1105 existing between the aperture width constantsection 1103 and the overlapping section A1101, the sum of thelongitudinal aperture widths changes as the position in the firstdirection x changes. The change in the sum of the longitudinal aperturewidth is linear. It is because the shapes of the overlapping regionsC1226R and 1326L of the sub-pixels 1200 and 1300 neighboring to thesub-pixel 1100 are in a right-angled triangle shape in Example 1.Provided that the range where the longitudinal aperture width changes inthe first direction x is V1, there are the maximum value Wh of thelongitudinal aperture width and the minimum value Wl of the longitudinalaperture width. As in the case of the first exemplary embodiment, thesum of the longitudinal aperture widths does not necessarily have to beconstant in Example 1.

Example 1 can also be expressed as follows. The overlapping regions A,B, and C include two longitudinal aperture width sum fluctuating regions(i.e., the overlapping regions B, C) where the sum of the longitudinalaperture widths with the two neighboring sub-pixels at the same positionin the first direction x continuously change, respectively, from roughlythe center of the overlapping regions A, B, and C towards the both endsin the first direction x. The sum of the longitudinal aperture widthwith the two neighboring sub-pixels in the overlapping regions A, B, andC is larger than the longitudinal aperture width in roughly the centerof the aperture part.

With Example 1, the similar effects as those of the first exemplaryembodiment can be acquired. That is, even in a case where the aperturepart is reduced as a whole and a case where the corner is rounded, whitemoiré is generated as in the case of the first exemplary embodiment sothat a fine stereoscopic display property can be achieved. Furthermore,unlike the cases of the first and second exemplary embodiments, thepositions of the corner of the aperture part of the sub-pixel and thatof the aperture part of the neighboring sub-pixel are different in thefirst direction in Example 1. Thus, the change in the sum of thelongitudinal aperture widths when the corner is rounded is smaller thanthe cases of the first and second exemplary embodiments. That is, in thecase of FIG. 4B, for example, the longitudinal aperture width changevalue Wq becomes still smaller. As described above, this is because theopposing aperture sides of the sub-pixel and the neighboring sub-pixelare disposed by being shifted in the first direction.

Further, particularly the shape and the size of the corner of theaperture part among the sub-pixel shape is susceptible to manufacturevariation. In the sub-pixel shape of Example 1, there are a smallernumber of the corners compared to those of the first and secondexemplary embodiments. Thus, with Example 1, the precision whenmanufacturing the sub-pixel shapes can be improved.

Fourth Exemplary Embodiment (Example 2)

Example 2 of the fourth exemplary embodiment will be described byreferring to FIG. 20A and FIG. 20B. As shown in FIG. 20A, in Example 2,sub-pixels 2200 and 2300 are disposed by neighboring to a sub-pixel 2100in the first direction x. The unit lenses of the lens 1 as the light-raycontrol modules are disposed at the positions corresponding to thesub-pixel 2100 and the neighboring sub-pixel 2300, and such structure isarranged repeatedly along the first direction x. Unlike Example 1 of thefourth exemplary embodiment, the positions of the sub-pixel 2100 and theneighboring sub-pixels 2200, 2300 in the second direction y coincidewith each other in Example 2.

As in the case of Example 1 of the fourth exemplary embodiment, inExample 2, each of the aperture parts 2110 (2210, 2310) of the twosub-pixels 2100 (2200, 2300) neighboring to each other in the firstdirection x includes: an overlapping region A2121 (2221, 2321), anoverlapping region B2125 (2225, 2325), and an overlapping region C2126(2226, 2326) which overlap with each other in the second direction y;and an aperture width constant region 2123 (2223, 2323) which does notoverlap with each other (a non-overlapping region). The overlappingregions B and C are the longitudinal aperture width sum fluctuatingregions. In the non-overlapping region, the longitudinal aperture width2113 (2213, 2313) is always constant regardless of the positions in thefirst direction x. In this respect, Example 2 is different from thefirst and second exemplary embodiments. The sum of the longitudinalaperture widths of the overlapping section A2101L of the sub-pixel 2100,“2111L+2211R”, the sum of the longitudinal aperture widths of theoverlapping section B2105L, “2115L+2216R”, and the sum of thelongitudinal aperture widths of the overlapping section C2106L,“2116L+2215R”, are larger than the longitudinal aperture width 2113 ofthe aperture width constant section 2103, respectively. Similarly, thesum of the longitudinal aperture widths of the overlapping sectionA2101R, “2111R+2311L”, the sum of the longitudinal aperture widths ofthe overlapping section B2105R, “2115R+2316L”, and the sum of thelongitudinal aperture widths of the overlapping section C2106R,“2116R+2315L”, are larger than the longitudinal aperture width 2113 ofthe aperture width constant section 2103, respectively.

In Example 2, the opposing aperture sides of the sub-pixel 2100 and theneighboring sub-pixel 2200 are also disposed by being shifted in thefirst direction x. Specifically, the corner part 2100 p of the sub-pixel2100 and the corner part 2200 q of the sub-pixel 2200 are shifted in thefirst direction x. Similarly, the corner part 2100 q of the sub-pixel2100 and the corner part 2200 p of the sub-pixel 2200 are shifted in thefirst direction x. Other structures of Example 2 are same as those ofExample 1 of the fourth exemplary embodiment.

The relation between the positions in the first direction x and thelongitudinal aperture widths (sum of the longitudinal aperture widths)in Example 2 is shown by a plot 042 in FIG. 20B. Provided that the rangewhere the longitudinal aperture width changes in the first direction xis V1 as in the case of Example 1 of the fourth exemplary embodiment,there are the maximum value Wh of the longitudinal aperture width andthe minimum value Wl of the longitudinal aperture width in the range V1.Thus, it is possible with Example 2 to achieve similar effects as thecase of Example 1 of the fourth exemplary embodiment. Other structures,operations, and effects of the fourth exemplary embodiment are same asthose of the first to third exemplary embodiments.

Fifth Exemplary Embodiment (Example 1)

Even though the shapes of sub-pixels vary in each of Examples of a fifthexemplary embodiment, those are referred to as the sub-pixels A and Bfor simplifying the explanation. Example 1 of the fifth exemplaryembodiment will be described by referring to FIG. 21A and FIG. 21B. Thesub-pixels in FIG. 21A are shown by schematically illustrating theaperture shape of the fourth exemplary embodiment (Example 1), and pixelelectrodes or common electrodes in a lateral electric field type liquidcrystal display device. The aperture shape of the sub-pixel is anisosceles trapezoid as in the case of the fourth exemplary embodiment(Example 1), and the neighboring sub-pixels have the aperture shapesthat are rotationally symmetrical at 180 degrees. Such sub-pixels arealternately arranged in the first direction x. Further, the sub-pixelsneighboring to each other in the second direction y also have theaperture shapes that are rotationally symmetrical at 180 degrees, andsuch sub-pixels are alternately arranged.

In FIG. 21A and FIG. 21B, there are sub-pixels A in which a long-sidedirection a2 of an electrode a1 forms an angle ψA with respect to theinitial alignment direction (first direction x) of the liquid crystaland sub-pixels B in which a long-side direction b2 of an electrode b1forms an angle ψB with respect to the initial alignment direction (firstdirection x) of the liquid crystal. Because it is the lateral electricfield type, an electric field direction a3 applied to the sub-pixel Aforms an angle ξA with respect to the initial alignment direction (firstdirection x) of the liquid crystal, and an electric field direction b3applied to the sub-pixel B forms an angle ξB with respect to the initialalignment direction (first direction x) of the liquid crystal. Thelong-side direction a2 is orthogonal to the electric field direction a3,and the long-side direction b2 is orthogonal to the electric fielddirection b3. Two sub-pixels A are placed along the first direction xand two sub-pixels B are placed neighboring to those. Thereby, thesub-pixels A and the sub-pixels B are arranged at a cycle of twosub-pixels. Similarly, along the second direction y, the sub-pixels Aand the sub-pixels B are arranged at a cycle of two sub-pixels.Particularly, the long sides of the isosceles trapezoids of the twosub-pixels A (or two sub-pixels B) neighboring along the seconddirection y oppose to each other, and have a same electrode angle.

Example 1 can also be expressed as follows. The sub-pixels A and B arelateral-field drive type liquid crystal display devices, and each ofthose includes striped electrodes a1 and b1 within the aperture part.The angle ψA between the long-side direction a2 of the electrode a1 ofthe sub-pixel A and the liquid crystal initial alignment (firstdirection x) is different from the angle ψB between the long-sidedirection b2 of the electrode b1 of the sub-pixel B that is for the sameviewpoint with the sub-pixel A and neighboring thereto in the firstdirection x and the liquid crystal initial alignment (first directionx).

The relation between the initial alignment of positive liquid crystal(ε//−ε⊥>0) and electrodes is schematically shown in FIG. 22A and FIG.22B. In the drawings, the initial alignment direction is in parallel tothe first direction x. A voltage is applied to the sub-pixel A in such amanner that the electric field direction a3 is at the angle ξA, and avoltage supplied to the sub-pixel B in such a manner that the electricfield direction b3 is at the angle ξB (FIG. 21B). Thus, when the voltageis applied, liquid molecules pm0 in the sub-pixel A rotatecounterclockwise from the initial alignment with respect to thesubstrate plane (arrow pa), while liquid molecules pm0 in the sub-pixelB rotate clockwise from the initial alignment with respect to thesubstrate plane (arrow pb). Therefore, as shown in FIG. 22C, whenobserved from a certain angle in the case where the sub-pixels A and thesub-pixel B are arranged periodically, the display is to be observedfrom both the major axis direction of the liquid crystal molecule pma(liquid crystal molecules pmb) of the sub-pixel A (sub-pixel B) and theminor axis direction of the liquid crystal molecule pmb (liquid crystalmolecule pma) of the sub-pixel B (sub-pixel A).

The relation between the initial alignment of negative liquid crystal(ε//−ε⊥<0) and electrodes is schematically shown in FIG. 22D and FIG.22E. In the drawings, the initial alignment direction is in parallel tothe second direction y. A voltage is applied to the sub-pixel A in sucha manner that the electric field direction becomes ξA, and the liquidcrystal molecules nm0 rotate counterclockwise from the initial alignmentwith respect to the substrate plane (arrow na). A voltage is applied tothe sub-pixel B in such a manner that the electric field directionbecomes U3, and the liquid crystal molecules nm0 rotate clockwise fromthe initial alignment with respect to the substrate plane (arrow nb).Therefore, as shown in FIG. 22F, when observed from a certain angle inthe case where the sub-pixels A and the sub-pixel B are arrangedperiodically, the display is to be observed from both the major axisdirection of the liquid crystal molecule nma (liquid crystal moleculesnmb) of the sub-pixel A (the sub-pixel B) and the minor axis directionof the liquid crystal molecule nmb (liquid crystal molecule nma) of thesub-pixel B (the sub-pixel A).

Considering a liquid crystal molecule as a refractive index ellipsoid,when viewing from the viewing field angle of the major axis direction ofthe liquid crystal with respect to the substrate plane and when viewingthe viewing field angle of the minor axis direction in a single domainstructure, the molecule is viewed bluish in the major axis directionwhile it is viewed yellowish in the minor axis direction. Note here thatthrough changing the electrode direction (applied electric fielddirection) for each sub-pixel, the liquid crystals are rotated in thedirections different from each other between the sub-pixel A and thesub-pixel B. Thus, the major axes and the minor axes of the refractiveindex ellipsoids are simultaneously viewed necessarily at any viewingfield angles. When ψA≠ψB, the axes of the refractive index ellipsoidscan be viewed from different directions and color compensation can bedone. In FIG. 21B, the electrode angle ψA of the sub-pixel A and theelectrode angle ψB of the sub-pixel B are in a line symmetric relationform each other (ψA=180°−ψB) with respect to the initial alignmentdirection of the liquid crystal. Under such relation, when a sameelectric field is applied to the sub-pixels A and B, the liquid crystalsof the sub-pixels A and B rotate in different rotating directions fromeach other at a same angle. Therefore, a still finer display propertycan be acquired.

In the case of the naked-eye type stereoscopic display device, there isstill a point to be studied further. It is because the emitted lightfrom each sub-pixel has the directivity due to the light-ray controlmodule such as a lens, and there are sub-pixels that cannot be visuallyrecognized from certain viewing field angles.

Example 1 is a case of a matrix of the sub-pixels which display2-viewpoints, in which the sub-pixel A and the sub-pixel B areneighboring to each other between the sub-pixels for the same viewpointand the electrode angles thereof are different from each other. In FIG.21A, all the sub-pixels are in the relation described above. With thisstructure, the sub-pixel A and the sub-pixel B are mutually recognizedat the same viewpoint and the major axes and the minor axes of therefractive index ellipsoids are viewed simultaneously. Therefore, a finestereoscopic display property can be acquired.

Fifth Exemplary Embodiment (Example 2)

Example 2 of the fifth exemplary embodiment will be described byreferring to FIG. 23A and FIG. 23B. Example 2 is different from Example1 of the fifth exemplary embodiment, and the aperture shape of thesub-pixels A and B is the same as that of the first exemplary embodiment(Example 1). Even when each of the aperture shapes of the first andsecond exemplary embodiments are used, it is possible with Example 2 toacquire a fine display property as in the case of Example 1 of the fifthexemplary embodiment.

Fifth Exemplary Embodiment (Example 3)

“The first direction (lateral direction of the drawings)” and “thesecond direction (vertical direction of the drawings) in Examples 3 to 5of the fifth exemplary embodiment correspond to “the first direction x”and “the second direction y” of the other drawings. FIG. 24A, FIG. 24B,and FIG. 24C are tables showing the structural examples of Example 3. InExample 3, the same-viewpoint sub-pixels neighboring to each other inthe first direction are two kinds of sub-pixels having differentelectrode angles from each other. FIG. 24A and FIG. 24B show the layoutof the sub-pixels A and the sub-pixels B of a matrix of the sub-pixelsin a case of 2-viewpoints, respectively. Specifically, the pixels of themost left end are a pixel column for the right-viewpoint, and theneighboring pixels on the right are a pixel column for theleft-viewpoint. Such columns are repeated thereafter to form a sub-pixelmatrix. Looking at the right-viewpoint pixel columns, the layout of theneighboring sub-pixels is changed alternately between the column of thesub-pixels A and the column of the sub-pixels B. Looking at the seconddirection, the sub-pixel A and the sub-pixel B are not changed with eachother. With this structure, the same-viewpoint sub-pixels neighboring toeach other in the first direction have different electrode angles formeach other. Thus, the major axes and the minor axes of the refractiveindex ellipsoids are to be simultaneously viewed at any viewing fieldangles after transmitted through the light-ray control module.

FIG. 24C shows the layout of the sub-pixels A and the sub-pixels B of amatrix of the sub-pixels in a case of a stereoscopic display device ofN-viewpoints. Note here that N is an integer of 2 or larger. Looking ata sub-pixel column for 1-viewpoint, the sub-pixel column of the mostleft end are all sub-pixels A, and a neighboring sub-pixel column for1-viewpoint are all sub-pixels B. Thereafter, the neighboring sub-pixelcolumns for 1-viewpoint are alternately changed between the sub-pixels Aand the sub-pixels B. The sub-pixel columns for other viewpoints arealso changed alternately between the neighboring sub-pixel columns.Looking at the second direction, the sub-pixels are not changed witheach other. However, even in the cases of N-viewpoints, it is alsopossible to change the sub-pixels alternately as in FIG. 21A or FIG.23A.

Fifth Exemplary Embodiment (Example 4)

FIG. 25A and FIG. 25B are tables showing the structural examples ofExample 4. In Example 4, the same-viewpoint sub-pixels neighboring toeach other in the first direction are two kinds of sub-pixels havingdifferent electrode angles from each other. Further, the two kinds ofsub-pixels are arranged in a cycle of one sub-pixel or two sub-pixels inthe second direction. FIG. 25A and FIG. 25B show the layout of thesub-pixels A and the sub-pixels B of a matrix of the sub-pixels in acase of 2-viewpoints, respectively. The same-viewpoint sub-pixelsneighboring to each other in the first direction are in the samestructure of the sub-pixel layout described in Examples 1 and 2 of thefifth exemplary embodiment. In FIG. 25A, the sub-pixel A and thesub-pixel B are changed alternately by every sub-pixel in the seconddirection. Further, in FIG. 25B, the sub-pixel A and the sub-pixel B arechanged alternately by every two sub-pixels in the second direction.FIG. 25B shows the structure same as the pixel layout shown in FIG. 21Aor FIG. 23.

Compared to the structures of FIG. 24A and FIG. 24B, the sub-pixels Aand the sub-pixel B are changed also in the second direction in thestructures of FIG. 25A and FIG. 25B. Thus, the major axes and the minoraxes of the refractive index ellipsoids are also viewed between thesub-pixels disposed in the second direction. Therefore, a still finerstereoscopic display property can be acquired.

Fifth Exemplary Embodiment (Example 5)

FIG. 26A and FIG. 26B are tables showing the structural examples ofExample 5. In Example 5, the same-viewpoint and same-color sub-pixelsneighboring to each other in the first direction are two kinds ofsub-pixels having different electrode angles from each other. FIG. 26Aand FIG. 26B show the layout of the sub-pixels A and the sub-pixels B ofa matrix of the sub-pixels in a case of 2-viewpoints, and each of thesub-pixels has a color display function which shows one of three colors,red (R), green (G), and blue (B). In FIG. 26A, each color is in avertical strip layout. In FIG. 26B, each color is in a lateral stripelayout.

The sub-pixel column of the most left end of FIG. 26A is a sub-pixelcolumn for the right-viewpoint and for displaying red, and the sub-pixelA therein is changed to the sub-pixel B alternately in the seconddirection. Further, in the sub-pixel column for the right-viewpoint andfor displaying red same as that sub-pixel column neighboring thereto inthe first direction, the sub-pixel A (sub-pixel B) is changed to thesub-pixel B (sub-pixel A) in the first direction. Thereafter, in thesub-pixel column for the right-viewpoint and for displaying red same asthat sub-pixel column neighboring thereto in the first direction, thesub-pixel A and the sub-pixel B are changed alternately in the firstdirection. In the columns of other viewpoints and other colors, thesub-pixel A and the sub-pixel B are alternately changed in the firstdirection in the same-viewpoint and same-color sub-pixel columnsneighboring to each other in the first direction.

In the meantime, in FIG. 26B, the sub-pixel column of the most left endis a sub-pixel column for the right-viewpoint. The sub-pixels on n-throw are the sub-pixels for displaying red, and the sub-pixels on the(n+1)-th row are the sub-pixels for displaying green. Thereafter, thethree colors are changed in the second direction from blue→red, ---.Note here that n is a natural number. The sub-pixel column forright-viewpoint neighboring to the sub-pixel column of the most left endin the first direction, the sub-pixels A are changed to sub-pixels B onthe n-th row (R), and the sub-pixels B are changed to the sub-pixels Aon the (n+1)-th row (G). In the other rows thereafter, the sub-pixels A(sub-pixels B) are also changed to the sub-pixels B (sub-pixels A) inthe same manner. Thus, in the structure of FIG. 26B, the sub-pixel A andthe sub-pixel B are alternately changed in the first direction in thesame-viewpoint and same-color sub-pixel columns neighboring to eachother in the first direction as in the case of FIG. 26A. The colordisplay function of the sub-pixels is not limited to displaying threecolors of red (R), green (G) and blue (B) but may be designed to displayfour or more colors (e.g., white (W) may be added to those threecolors).

Each of Examples of the fifth exemplary embodiment are examples in whichthe present invention is embodied with a liquid crystal display device,and the Examples can be applied not only to the fifth exemplaryembodiment but also to the other exemplary embodiments. Thus, each ofExamples of the fifth exemplary embodiment is not limited only to thesub-pixel shape and the sub-pixel layout shown in FIG. 21A and FIG. 23Abut may be combined arbitrarily with the sub-pixel shapes and thesub-pixel layout of the other exemplary embodiments. Other structures,operations, and effects of the fifth exemplary embodiment are same asthose of the first to fourth exemplary embodiments.

A plurality of structural elements described in each of the aboveexemplary embodiments are not limited to those specifically describedabove. For example, in the explanations above, the light-ray controlmodule is described as the structure using a lens. However, thelight-ray control module is not limited to that. It is also possible touse an electro-optical element such as a liquid crystal lens or aparallax barrier. Furthermore, some of the structural elements shown ineach of the exemplary embodiments can be omitted or the structuralelements according to the different exemplary embodiments can becombined as appropriate.

A part of or a whole part of each of the above-described exemplaryembodiments can be depicted as in following Supplementary Notes.However, it is to be noted that the present invention is not limitedonly to the following structures.

(Supplementary Note 1)

A stereoscopic display device, which includes:

a display panel including sub-pixels with optical aperture parts beingdisposed in a matrix form in a first direction and a second directionthat is roughly perpendicular to the first direction; and

a light-ray control module which is provided by opposing to the displaypanel for controlling light rays towards the first direction, wherein:

each of the aperture parts of two of the sub-pixels neighboring to eachother in the first direction includes an overlapping region overlappingwith each other in the second direction and an non-overlapping regionnot overlapping with each other;

provided that a width of the aperture part in the second direction isdefined as a longitudinal aperture width, the non-overlapping regionincludes an aperture width fluctuating region where the longitudinalaperture width changes continuously from roughly a center of theaperture part towards both ends of the first direction, respectively;and

a sum of the longitudinal aperture widths of the two overlapping regionsoverlapping with each other located at a same position in the firstdirection is larger than the longitudinal aperture width in roughly thecenter of the aperture part.

(Supplementary Note 2)

The stereoscopic display device as depicted in Supplementary Note 1,wherein

the sum of the longitudinal aperture widths of the two overlappingregions overlapping with each other located at a same position in thefirst direction is same at any positions in the first direction.

(Supplementary Note 3)

The stereoscopic display device as depicted in Supplementary Note 1 or2, wherein

the sum of the longitudinal aperture widths of the two overlappingregions overlapping with each other located at a same position in thefirst direction is within a range that is over 1 time and equal to 1.12times or less of the longitudinal aperture width in roughly the centerof the aperture part.

(Supplementary Note 4)

The stereoscopic display device as depicted in any one of SupplementaryNotes 1 to 3, wherein

provided that peripheral sides of the aperture part are defined asaperture sides, all the aperture sides included in the aperture widthfluctuating region are in parallel to none of the aperture sidesincluded in the overlapping region.

(Supplementary Note 5)

The stereoscopic display device as depicted in any one of SupplementaryNotes 1 to 4, wherein

the non-overlapping region includes an aperture width constant regionwhere the longitudinal aperture width is same at any positions in thefirst direction.

(Supplementary Note 6)

The stereoscopic display device as depicted in any one of SupplementaryNotes 1 to 5, wherein

provided that a maximum value of a difference between a position in thesecond direction at one end of the aperture part and a position in thesecond direction at other end of the aperture part is defined as alongitudinal aperture section, the longitudinal aperture section islarger than a maximum value of the longitudinal aperture width.

(Supplementary Note 7)

The stereoscopic display device as depicted in Supplementary Note 6,wherein

the positions at the one end and the other end in the second directionforming the longitudinal aperture section are same between the apertureparts that are neighboring to each other in the first direction.

(Supplementary Note 8)

A stereoscopic display device, which includes:

a display panel including sub-pixels with optical aperture parts beingdisposed in a matrix form in a first direction and a second directionthat is roughly perpendicular to the first direction; and

a light-ray control module which is provided by opposing to the displaypanel for controlling light rays towards the first direction, wherein:

each of the aperture parts of two of the sub-pixels neighboring to eachother in the first direction includes an overlapping region overlappingwith each other in the second direction and an non-overlapping regionnot overlapping with each other;

provided that a width of the aperture part in the second direction isdefined as a longitudinal aperture width, the overlapping regionincludes two longitudinal aperture width sum fluctuating regions where asum of the longitudinal aperture widths of the two neighboringsub-pixels at a same position in the first direction changescontinuously from roughly a center of the overlapping region towardsboth ends of the first direction, respectively; and

a sum of the longitudinal aperture widths of the overlapping region islarger than the longitudinal aperture width in roughly the center of theaperture part.

(Supplementary Note 9)

The stereoscopic display device as depicted in Supplementary Note 1 or8, wherein:

the sub-pixel is a lateral-field drive type liquid crystal displaydevice;

striped electrodes are provided within the aperture part; and

an angle formed between liquid crystal initial alignment and a long-sidedirection of the electrode of the sub-pixel is different from an angleformed between the liquid crystal initial alignment and a long-sidedirection of the electrode of the sub-pixel which is for a sameviewpoint with that sub-pixel and neighboring thereto in the firstdirection.

INDUSTRIAL APPLICABILITY

The present invention can be utilized to any types of stereoscopicdisplay devices as long as the devices provide stereoscopic images tonaked-eye observers, such as a liquid crystal display, an organic ELdisplay, a plasma display, and the like.

What is claimed is:
 1. A stereoscopic display device, comprising: adisplay panel including sub-pixels with optical aperture parts beingdisposed in a matrix form in a first direction and a second directionthat is perpendicular to the first direction; and a light-ray controlmodule which is provided to the display panel for controlling light raystowards the first direction, wherein: provided that two of thesub-pixels neighboring to each other in the first direction are definedas a first sub-pixel and a second sub-pixel respectively, each of theaperture parts of the first sub-pixel and the second sub-pixel includesan overlapping region where the first sub-pixel and the second sub-pixeloverlap with each other in the second direction and a non-overlappingregion where the first sub-pixel and the second sub-pixel do not overlapwith each other; wherein a width of the aperture part provided in thesecond direction is defined as a longitudinal aperture width, thenon-overlapping region includes an aperture width fluctuating regionwhere the longitudinal aperture width changes continuously from a centerregion of the aperture part to both ends of the non-overlapping regionin the first direction, respectively and wherein the center regioncomprises an aperture width constant region where the longitudinalaperture width is same at any positions in the first direction; and asum of the longitudinal aperture widths of the overlapping regions ofthe first sub-pixel and the second sub-pixel located at a same positionin the first direction is larger than the longitudinal aperture width inthe aperture width constant region of the aperture part.
 2. Thestereoscopic display device as claimed in claim 1, wherein the sum ofthe longitudinal aperture widths of the overlapping regions of the firstsub-pixel and the second sub-pixel located at a same position in thefirst direction is same at any positions in the first direction.
 3. Thestereoscopic display device as claimed in claim 1, wherein the sum ofthe longitudinal aperture widths of the overlapping regions of the firstsub-pixel and the second sub-pixel located at a same position in thefirst direction is within a range that is over 1 time and equal to 1.12times or less of the longitudinal aperture width in the aperture widthconstant region of the aperture part.
 4. The stereoscopic display deviceas claimed in claim 1, wherein peripheral sides of the aperture part areprovided and are defined as aperture sides, all the aperture sidesincluded in the aperture width fluctuating region are in parallel tonone of the aperture sides included in the overlapping region.
 5. Thestereoscopic display device as claimed in claim 1, wherein a maximumvalue of a difference between a position in the second direction at oneend of the aperture part and a position in the second direction atanother end of the aperture part is defined as a longitudinal aperturesection, and the longitudinal aperture section is larger than a maximumvalue of the longitudinal aperture width.
 6. The stereoscopic displaydevice as claimed in claim 5, wherein the positions at the one end andthe other end in the second direction forming the longitudinal aperturesection are same between the aperture parts that are neighboring to eachother in the first direction.
 7. The stereoscopic display device asclaimed in claim 1, wherein: the sub-pixel is a lateral-field drive typeliquid crystal display device; striped electrodes are provided withinthe aperture part; and an angle formed between liquid crystal initialalignment and a long-side direction of the electrode of the sub-pixel isdifferent from an angle formed between the liquid crystal initialalignment and a long-side direction of the electrode of the sub-pixelwhich is for a same viewpoint with that sub-pixel and neighboringthereto in the first direction.